Saw a guy that we used to play football together 1st time after 12 years inside a supermarket. Spoke for about 10 minutes. Gave him my number. Didn't remember his named and didn't want to offend him what his name was so I searched him and found him in Facebook. Didn't send a friend request. After 3 days Instagram suggested him to me. No mutual connections. How does the algorithm worked here? Was it because we exchanged numbers? Instagram found we were talking for about 10 minutes? Was it about I searched him on Facebook? Instagram and Facebook aren't connected.